Douglasia idahoensis is known only from a narrow region of northern Idaho. Its fleshy leaves and multiflowered inflorescence are distinctive. Morphologically and geographically, it is closest to D. laevigata; molecular genetic analyses show a closer relationship to D. montana. The single chromosome count of n = 18 for this species is somewhat questionable because it represents an anomaly for the genus, which typically has a base number of 19; this count should be verified.